Ethylene Polymer Foam Composition for Lightweight Footwear
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Solution Overview
Problem
Crosslinked foams made from ethylene/vinyl acetate copolymers have high specific gravity and large compression set, leading to heavy shoe soles with decreased mechanical strength and impact resilience over time.
Innovation Solution
A foam composition comprising an ethylene polymer with an ethylene/α-olefin copolymer and an ethylene/C3-20 α-olefin/non-conjugated polyene copolymer, crosslinked using a radical generator and crosslinking assistant, with a specific gravity range of 0.03 to 0.30 and compression set satisfying the formula CS≦−279×(d)+95, where d is the specific gravity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If crosslinked foams are made from ethylene/vinyl acetate copolymers to achieve flexibility and mechanical strength, then the foam has high mechanical strength, but the specific gravity increases and compression set becomes large
Solution Approach 1:
The invention changes the chemical composition parameters by replacing ethylene/vinyl acetate copolymer with ethylene/α-olefin copolymer having specific density (0.910-0.940 g/cm³) and melt flow rate (0.5-10 g/10min) within controlled ranges, achieving lower specific gravity while maintaining mechanical strength through optimized polymer parameters
Solution Approach 2:
The invention uses a composite system combining ethylene/α-olefin copolymer with specific additives (peroxide crosslinking agent, foaming agent, lubricant) to create a crosslinked foam structure that achieves both low specific gravity and high mechanical strength through synergistic material composition
2Ease of operation
If crosslinked foams are made from ethylene/vinyl acetate copolymers to achieve flexibility, then the foam has flexibility, but the compression set becomes large
Solution Approach 1:
The invention changes the polymer parameters by selecting ethylene/α-olefin copolymer with specific density and melt flow rate ranges, and controlling the vinyl acetate content to achieve optimal balance between flexibility and compression resistance
Solution Approach 2:
The invention replaces mechanical crosslinking with chemical crosslinking using peroxide agents, creating a more stable crosslinked network that reduces compression set while preserving flexibility through chemical bond formation rather than physical entanglement
3Weight of moving object
If the foam specific gravity is reduced to achieve lightweight footwear, then the weight decreases, but the mechanical strength and impact resilience decrease
Solution Approach 1:
The invention optimizes polymer parameters including density (0.910-0.940 g/cm³) and melt flow rate (0.5-10 g/10min) to achieve the lowest possible specific gravity while maintaining sufficient mechanical strength and impact resilience for footwear applications
Solution Approach 2:
The invention uses peroxide crosslinking to create a three-dimensional network structure that provides mechanical strength and impact resilience independent of density, allowing lightweight foam structure to achieve high strength through chemical crosslinking rather than mechanical interlocking
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting foam has a low specific gravity, small compression set, and uniform quality, suitable for lightweight footwear components with improved impact resilience and durability.
Implementation Method 1
molecular chains in the foam are linked to each other by crosslinking reaction of the resin
Implementation Method 2
foaming a resin provides lightweight but results in a foam having low mechanical strength
Data Source
AI summary
[Objects] It is an object to provide a foam having a low specific gravity and a small compression set, more preferably a foam having a low specific gravity, a small compression set and uniform quality, a foaming composition, and applications of the foam.[Means for Solution] The foam is obtained by foaming an olefin polymer, wherein the foam has a specific gravity (d) in the range of 0.03 to 0.30, and a compression set (CS, %) and the specific gravity (d) satisfy the formula of CS≦−279×(d)+95. The foam is preferably obtained from a foaming composition that includes an ethylene polymer (A) including a specific ethylene/α-olefin copolymer (A1) and an ethylene/polar monomer copolymer (A2) in a specific mass ratio, and a specific ethylene/C3-20 α-olefin/non-conjugated polyene copolymer (B).